Arc tube mount



April 27, 1954 E. C, M -r 2,677,068

ARC TUBE MOUNT Filed Dec. 29, 1951 Inventor": Ernest C. Martc,

His Attorney Patented Apr. 27, 1954 UNITED STATES ATENT OFFICE General New York Electric Company, a corporation of Appiication December 29, 1951, Serial No. 264,076

3 Claims. (Cl. 31325) The present invention relates to high pressure electric discharge lamps having .an inner arc tube of vitreous material, an outer vitreous envelope and a mount supporting said tube in said envelope.

In the co-pending application Serial No. 246,231, filed September 12, 1951, of Paul A. Dell, which application is assigned to the assignee of the present application, a lamp of this type is disclosed and claimed wherein the arc tube has at each of its ends an externally extending fiat press seal portion and the mount includes two channel shaped metal support members each provided with an opening in the bottom of the channel to receive the outer ends of the said flat portions of the arc tube. Spring fingers are stamped out of the bottom of the channel and engage the said fiat end portions of the tube.

As pointed out in the co-pending application, since the metal support members disclosed and claimed therein do not engage the hot tubular wall of the arc tube but rather engage the outer ends of the comparatively cool flat seal portions at the ends of the tube difficulties characteristic of prior lamps having metal supports engaging the hot tubular part of the arc tube are avoided. Such difiiculties include electrolysisof the vitreous material of the arc tube, thermal shock to the tube and the conduction of heat from the tube by the supports. The advantages of the novel structure of the lamp of the co-pending application also include a shorter warm-up time, that is, the time required for the lamp to attain its normal high operating vapor pressure after starting of the discharge, and elimination of distor: tion of the metal supports by the intense heat at th tubular portion of the arc tube.

An object of the present invention is to provide arc tube support members for use in lamps of the above type which are inexpensive to manufacture by mass production methods and which are readily attachable to the mount for the arc tube in the envelope. Another object of the invention is to provide an arc tube mount includme such members. Further objects and advantages of the invention will appear from the following detailed description of a species thereof.

In the drawing accompanying and forming part of this specification a species of the invention is shown in which Fig. 1 is a front elevational view of a discharge lamp of the high pressure type in which the support members for the inner arc tube embody the present invention, Fig. 2 is a front elevational view on an enlarged scale of one of said support members and Fig. 3

is an auxiliary elevational view of the support member shown in Fig. 2 taken at an angle of 30 degrees as indicated by the arrow.

Referring to Fig. 1 of the drawing the lamp comprises an outer vitreous envelope l having a re-entrant stem 2 through the pinched or pressed part 3 of which extend the leading-in wires 4 and 5 which are connected at their outer ends to the contacts on the usual screw type base 6 of the lamp and terminate within the outer envelope for connection to the terminals of the inner arc tube 1.

Th inner arc tube 1 is made of hard vitreous material, such as quartz, and has sealed therein at opposite ends thereof a pair of main discharge supporting electrodes 8 and 9 of tungsten and material of higher electron emissivity, such as alkaline earth oxide and/or'thorium, the inleads I! and I 2 of which constitute the arc tube terminals. An auxiliary starting electrode Iii is sealed into one end of the tube 1 adjacent the main electrode 3. The current inlead wires H, I2, and 13 for said electrodes 8, 9 and i9, respectively, have a thin flattened section hermetically united with the pinched tube portions 14 and I5 extending outwardly from the arc tube 1 as described and claimed in the co-pending application of Edward B. Noel and Paul A. Dell, Serial No. 244,818, filed September 1, 1951, titled Ribbon Lead Construction, and assigned to the assignee of this application. In the watt size the arc tube 1 has a filling of starting gas, such as argon at a pressure of 20 millimeters, and a measured quantity of mercury sufficient to produce a high pressure, unsaturated vapor at mosphere at the operating temperature of the arc tube 1.

The mount for the arc tube 1 within the outer envelope I comprises a harness made up of a U- shaped stiii metal wire having its bent center portion I6 welded to the inlead 4 of stem 2 and its parallel legs I!- and i8 extending longitudinally of the arc tube I and terminating at the opposite end of the outer envelope I. A pair or spring members l9 and 20 press against the envelope l and are welded to the free ends of the legs I! and I 8. The U-shaped support is thus firmly held in position in the envelope l.

The are tube 1 is attached to the U-shaped support by transverse metal support members 2| welded to the legs I? and ill of the U-shaped support and engaging the corners of the outer ends of the pinched portions l4 and I5 of the tube 1. The supports 2| at each end of the tube 1 are identical in structure and are constituted by flat strips of metal, such as nickel plated iron or chrome iron, each having a pair of spaced ears or lugs 22 and 23 punched out of its central portion and bent in a curve to fit and. engage the said corners of the pinched parts l4 and it of the tube 1.

The support members may be made in a single punching operation from a strip of metal and are thus susceptible of mass production at low cost.

Further, the outer end portions of the members 2| may be attached to both legs ll and it of the U-shaped mount in a single operation by welding while being held in proper position with respect to the said legs by a jig to minimize the cost of assembly.

The curved ears 22 and 23 of the support members 21 are cut and bent in such manner that the end thereof integral with the member 25 is at an angle of about 30 with respect to the lcngitudinal axis of the strip member 2i and said ears incline toward each other as best shown in Figs. 2 and 3. Thus, when the arc tube 1 is positions-:1 in the amount including a pair of support me bers 2!, relative movement between the said tube 1 and the said mount either longitudinally or laterally of the tube 1 is prevented in a positive manner and the tube '5 is firmly supported by the amount in the envelope I.

In order to allow for expansion of the vitreous members and the metal members of the lamp at different rates during service I prefer to allow slight play between the corners of the pinched portions M and I5 of the tube 1 and the cars 32 and 23 of the supports 2! to prevent fracture of the quartz tube I and distortion of the metal supports 2|.

Positioning the transverse flat strip support members 2| in a plane parallel to the axis cf the tube 1 provides maximum strength for minimum thickness of the strip while providing also the necessary rigidity for supporting the arc tube 5 in a predetermined position within the envelope l. The thin support members 2! so positioned also offer minimum shadow casting obstruction to the light emitted by the discharge axially or" the arc tube 1.

The electrical connections between the electrodes 8, 9 and I and the current inleads i and are made in the conventional manner. Main electrode 9 is connected through its inlead i2 and the flexible conductor 24 to the leg I! of the U- shaped mount, the center portion It of which is welded to the inner end of current lead it. The main electrode 8 is connected through its inlead l i and the flexible conductor 25 to the inner end of inlead 5. The au 'liary electrode it is electrically connected to the main electrode 9 through its inlead l3, the flexible conductor 2%, the resistor 21 and the stiff wire conductor 28 welded to the leg [1 of the U-shaped mount.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A mount for a straight vitreous arc tube having at each end an external flat press seal portion, said mount comprising a pair of spaced parallel substantially rigid metal wires and means to secure said tube longitudinally between. said wires, said means consisting of a pair of thin metal flat strips extending transversely of and substantially in the plane including said wires and attached to said wires with their fiat sides against said wires, each of said strips having a pair of integral curved ears spaced apart longitudinally thereon, extending generally toward a longitudinal edge thereof and being inclined slightly toward each other, said strips being attached to said wires with their ears directed to the arc tube mounting space between said wires to provide seats for the outer end corners of the fiat press portions of the arc tube.

2. A mount for a straight vitreous arc tube having at each end an external fiat press seal portion, said mount comprising a pair of spaced parallel substantially rigid metal wires and means to secure said tube longitudinally between said wires, said means consisting of a pair of thin metal fiat strips extending transversely of and substantially in the plane including said wires and attached to said wires with their fiat sides against said wires, each of said strips having longitudinally spaced portions thereof cut and bent outwardly to form a pair of curved ears extending generally toward a longitudinal edge of the strip and being inclined toward each other, said strips being attached to said wires with their ears directed toward the arc tube mounting space between said wires to provide seats for the outer end corners of the flat press portions of the arc tube.

3. A support member for a vitreous arc tube having fiat external press seal portions at its ends, said support member consisting of a thin metal fiat strip having longitudinally spaced portions thereof cut and bent outwardly to form curved ears extending generally in the direction of a longitudinal edge of said strip and being inclined toward each other, the ends of said ears being spaced apart from each other and from said strip a suflicient distance to engage the outer corners of the flat press seal portion at one end of said arc tube.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,103,029 Davies Dec. 21, 1937 2,240,333 Hodge Apr. 29, 194i 2,491,868 Martt Dec. 20, 1949 FOREIGN PATENTS Number Country Date 110,747 Australia May 31, 1940 

